详解如何用详解如何用HTML5 Canvas API控制图片的缩放变换控制图片的缩放变换
缩放变换scale(sx,sy)传入两个参数,分别是水平方向和垂直方向上对象的缩放倍数。例如context.scale(2,2)就是对图像放大
两倍。其实,看上去简单,实际用起来还是有一些问题的。我们来看一段代码:
JavaScript Code复制内容到剪贴板
<!DOCTYPE html>
<html lang="zh">
<head>
<meta charset="UTF-8">
<title>缩放变换</title>
<style>
body { background: url("./images/bg3.jpg") repeat; }
#canvas { border: 1px solid #aaaaaa; display: block; margin: 50px auto; }
</style>
</head>
<body>
<div id="canvas-warp">
<canvas id="canvas">
你的浏览器居然不支持Canvas?!赶快换一个吧!!
</canvas>
</div>
<script>
window.onload = function(){
var canvas = document.getElementById("canvas");
canvas.width = 800;
canvas.height = 600;
var context = canvas.getContext("2d");
context.fillStyle = "#FFF";
context.fillRect(0,0,800,600);
context.strokeStyle = "red";
context.lineWidth = 5;
for(var i = 1; i < 4; i++){
context.save();
context.scale(i,i);
context.strokeRect(50,50,150,100);
context.restore();
}
};
</script>
</body>
</html>
运行结果:
评论0
最新资源